X-Git-Url: https://arthur.barton.de/cgi-bin/gitweb.cgi?p=netatalk.git;a=blobdiff_plain;f=libevent%2Fepoll.c;fp=libevent%2Fepoll.c;h=2d4aebfbdd3169d74dc04dc8c8933746d180c867;hp=0000000000000000000000000000000000000000;hb=9c8a21a5a13808bab520bd257b3d0a6fe16c6b07;hpb=4cafdfb9f307e9cc6131a79d09011ef09f3b8f20

diff --git a/libevent/epoll.c b/libevent/epoll.c
new file mode 100644
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--- /dev/null
+++ b/libevent/epoll.c
@@ -0,0 +1,470 @@
+/*
+ * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
+ * Copyright 2007-2010 Niels Provos, Nick Mathewson
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "event2/event-config.h"
+
+#include <stdint.h>
+#include <sys/types.h>
+#include <sys/resource.h>
+#ifdef _EVENT_HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
+#include <sys/queue.h>
+#include <sys/epoll.h>
+#include <signal.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#ifdef _EVENT_HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+
+#include "event-internal.h"
+#include "evsignal-internal.h"
+#include "event2/thread.h"
+#include "evthread-internal.h"
+#include "log-internal.h"
+#include "evmap-internal.h"
+#include "changelist-internal.h"
+
+struct epollop {
+	struct epoll_event *events;
+	int nevents;
+	int epfd;
+};
+
+static void *epoll_init(struct event_base *);
+static int epoll_dispatch(struct event_base *, struct timeval *);
+static void epoll_dealloc(struct event_base *);
+
+static const struct eventop epollops_changelist = {
+	"epoll (with changelist)",
+	epoll_init,
+	event_changelist_add,
+	event_changelist_del,
+	epoll_dispatch,
+	epoll_dealloc,
+	1, /* need reinit */
+	EV_FEATURE_ET|EV_FEATURE_O1,
+	EVENT_CHANGELIST_FDINFO_SIZE
+};
+
+
+static int epoll_nochangelist_add(struct event_base *base, evutil_socket_t fd,
+    short old, short events, void *p);
+static int epoll_nochangelist_del(struct event_base *base, evutil_socket_t fd,
+    short old, short events, void *p);
+
+const struct eventop epollops = {
+	"epoll",
+	epoll_init,
+	epoll_nochangelist_add,
+	epoll_nochangelist_del,
+	epoll_dispatch,
+	epoll_dealloc,
+	1, /* need reinit */
+	EV_FEATURE_ET|EV_FEATURE_O1,
+	0
+};
+
+#define INITIAL_NEVENT 32
+#define MAX_NEVENT 4096
+
+/* On Linux kernels at least up to 2.6.24.4, epoll can't handle timeout
+ * values bigger than (LONG_MAX - 999ULL)/HZ.  HZ in the wild can be
+ * as big as 1000, and LONG_MAX can be as small as (1<<31)-1, so the
+ * largest number of msec we can support here is 2147482.  Let's
+ * round that down by 47 seconds.
+ */
+#define MAX_EPOLL_TIMEOUT_MSEC (35*60*1000)
+
+static void *
+epoll_init(struct event_base *base)
+{
+	int epfd;
+	struct epollop *epollop;
+
+	/* Initialize the kernel queue.  (The size field is ignored since
+	 * 2.6.8.) */
+	if ((epfd = epoll_create(32000)) == -1) {
+		if (errno != ENOSYS)
+			event_warn("epoll_create");
+		return (NULL);
+	}
+
+	evutil_make_socket_closeonexec(epfd);
+
+	if (!(epollop = mm_calloc(1, sizeof(struct epollop))))
+		return (NULL);
+
+	epollop->epfd = epfd;
+
+	/* Initialize fields */
+	epollop->events = mm_calloc(INITIAL_NEVENT, sizeof(struct epoll_event));
+	if (epollop->events == NULL) {
+		mm_free(epollop);
+		return (NULL);
+	}
+	epollop->nevents = INITIAL_NEVENT;
+
+	if ((base->flags & EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST) != 0 ||
+	    ((base->flags & EVENT_BASE_FLAG_IGNORE_ENV) == 0 &&
+		evutil_getenv("EVENT_EPOLL_USE_CHANGELIST") != NULL))
+		base->evsel = &epollops_changelist;
+
+	evsig_init(base);
+
+	return (epollop);
+}
+
+static const char *
+change_to_string(int change)
+{
+	change &= (EV_CHANGE_ADD|EV_CHANGE_DEL);
+	if (change == EV_CHANGE_ADD) {
+		return "add";
+	} else if (change == EV_CHANGE_DEL) {
+		return "del";
+	} else if (change == 0) {
+		return "none";
+	} else {
+		return "???";
+	}
+}
+
+static const char *
+epoll_op_to_string(int op)
+{
+	return op == EPOLL_CTL_ADD?"ADD":
+	    op == EPOLL_CTL_DEL?"DEL":
+	    op == EPOLL_CTL_MOD?"MOD":
+	    "???";
+}
+
+static int
+epoll_apply_one_change(struct event_base *base,
+    struct epollop *epollop,
+    const struct event_change *ch)
+{
+	struct epoll_event epev;
+	int op, events = 0;
+
+	if (1) {
+		/* The logic here is a little tricky.  If we had no events set
+		   on the fd before, we need to set op="ADD" and set
+		   events=the events we want to add.  If we had any events set
+		   on the fd before, and we want any events to remain on the
+		   fd, we need to say op="MOD" and set events=the events we
+		   want to remain.  But if we want to delete the last event,
+		   we say op="DEL" and set events=the remaining events.  What
+		   fun!
+		*/
+
+		/* TODO: Turn this into a switch or a table lookup. */
+
+		if ((ch->read_change & EV_CHANGE_ADD) ||
+		    (ch->write_change & EV_CHANGE_ADD)) {
+			/* If we are adding anything at all, we'll want to do
+			 * either an ADD or a MOD. */
+			events = 0;
+			op = EPOLL_CTL_ADD;
+			if (ch->read_change & EV_CHANGE_ADD) {
+				events |= EPOLLIN;
+			} else if (ch->read_change & EV_CHANGE_DEL) {
+				;
+			} else if (ch->old_events & EV_READ) {
+				events |= EPOLLIN;
+			}
+			if (ch->write_change & EV_CHANGE_ADD) {
+				events |= EPOLLOUT;
+			} else if (ch->write_change & EV_CHANGE_DEL) {
+				;
+			} else if (ch->old_events & EV_WRITE) {
+				events |= EPOLLOUT;
+			}
+			if ((ch->read_change|ch->write_change) & EV_ET)
+				events |= EPOLLET;
+
+			if (ch->old_events) {
+				/* If MOD fails, we retry as an ADD, and if
+				 * ADD fails we will retry as a MOD.  So the
+				 * only hard part here is to guess which one
+				 * will work.  As a heuristic, we'll try
+				 * MOD first if we think there were old
+				 * events and ADD if we think there were none.
+				 *
+				 * We can be wrong about the MOD if the file
+				 * has in fact been closed and re-opened.
+				 *
+				 * We can be wrong about the ADD if the
+				 * the fd has been re-created with a dup()
+				 * of the same file that it was before.
+				 */
+				op = EPOLL_CTL_MOD;
+			}
+		} else if ((ch->read_change & EV_CHANGE_DEL) ||
+		    (ch->write_change & EV_CHANGE_DEL)) {
+			/* If we're deleting anything, we'll want to do a MOD
+			 * or a DEL. */
+			op = EPOLL_CTL_DEL;
+
+			if (ch->read_change & EV_CHANGE_DEL) {
+				if (ch->write_change & EV_CHANGE_DEL) {
+					events = EPOLLIN|EPOLLOUT;
+				} else if (ch->old_events & EV_WRITE) {
+					events = EPOLLOUT;
+					op = EPOLL_CTL_MOD;
+				} else {
+					events = EPOLLIN;
+				}
+			} else if (ch->write_change & EV_CHANGE_DEL) {
+				if (ch->old_events & EV_READ) {
+					events = EPOLLIN;
+					op = EPOLL_CTL_MOD;
+				} else {
+					events = EPOLLOUT;
+				}
+			}
+		}
+
+		if (!events)
+			return 0;
+
+		memset(&epev, 0, sizeof(epev));
+		epev.data.fd = ch->fd;
+		epev.events = events;
+		if (epoll_ctl(epollop->epfd, op, ch->fd, &epev) == -1) {
+			if (op == EPOLL_CTL_MOD && errno == ENOENT) {
+				/* If a MOD operation fails with ENOENT, the
+				 * fd was probably closed and re-opened.  We
+				 * should retry the operation as an ADD.
+				 */
+				if (epoll_ctl(epollop->epfd, EPOLL_CTL_ADD, ch->fd, &epev) == -1) {
+					event_warn("Epoll MOD(%d) on %d retried as ADD; that failed too",
+					    (int)epev.events, ch->fd);
+					return -1;
+				} else {
+					event_debug(("Epoll MOD(%d) on %d retried as ADD; succeeded.",
+						(int)epev.events,
+						ch->fd));
+				}
+			} else if (op == EPOLL_CTL_ADD && errno == EEXIST) {
+				/* If an ADD operation fails with EEXIST,
+				 * either the operation was redundant (as with a
+				 * precautionary add), or we ran into a fun
+				 * kernel bug where using dup*() to duplicate the
+				 * same file into the same fd gives you the same epitem
+				 * rather than a fresh one.  For the second case,
+				 * we must retry with MOD. */
+				if (epoll_ctl(epollop->epfd, EPOLL_CTL_MOD, ch->fd, &epev) == -1) {
+					event_warn("Epoll ADD(%d) on %d retried as MOD; that failed too",
+					    (int)epev.events, ch->fd);
+					return -1;
+				} else {
+					event_debug(("Epoll ADD(%d) on %d retried as MOD; succeeded.",
+						(int)epev.events,
+						ch->fd));
+				}
+			} else if (op == EPOLL_CTL_DEL &&
+			    (errno == ENOENT || errno == EBADF ||
+				errno == EPERM)) {
+				/* If a delete fails with one of these errors,
+				 * that's fine too: we closed the fd before we
+				 * got around to calling epoll_dispatch. */
+				event_debug(("Epoll DEL(%d) on fd %d gave %s: DEL was unnecessary.",
+					(int)epev.events,
+					ch->fd,
+					strerror(errno)));
+			} else {
+				event_warn("Epoll %s(%d) on fd %d failed.  Old events were %d; read change was %d (%s); write change was %d (%s)",
+				    epoll_op_to_string(op),
+				    (int)epev.events,
+				    ch->fd,
+				    ch->old_events,
+				    ch->read_change,
+				    change_to_string(ch->read_change),
+				    ch->write_change,
+				    change_to_string(ch->write_change));
+				return -1;
+			}
+		} else {
+			event_debug(("Epoll %s(%d) on fd %d okay. [old events were %d; read change was %d; write change was %d]",
+				epoll_op_to_string(op),
+				(int)epev.events,
+				(int)ch->fd,
+				ch->old_events,
+				ch->read_change,
+				ch->write_change));
+		}
+	}
+	return 0;
+}
+
+static int
+epoll_apply_changes(struct event_base *base)
+{
+	struct event_changelist *changelist = &base->changelist;
+	struct epollop *epollop = base->evbase;
+	struct event_change *ch;
+
+	int r = 0;
+	int i;
+
+	for (i = 0; i < changelist->n_changes; ++i) {
+		ch = &changelist->changes[i];
+		if (epoll_apply_one_change(base, epollop, ch) < 0)
+			r = -1;
+	}
+
+	return (r);
+}
+
+static int
+epoll_nochangelist_add(struct event_base *base, evutil_socket_t fd,
+    short old, short events, void *p)
+{
+	struct event_change ch;
+	ch.fd = fd;
+	ch.old_events = old;
+	ch.read_change = ch.write_change = 0;
+	if (events & EV_WRITE)
+		ch.write_change = EV_CHANGE_ADD |
+		    (events & EV_ET);
+	if (events & EV_READ)
+		ch.read_change = EV_CHANGE_ADD |
+		    (events & EV_ET);
+
+	return epoll_apply_one_change(base, base->evbase, &ch);
+}
+
+static int
+epoll_nochangelist_del(struct event_base *base, evutil_socket_t fd,
+    short old, short events, void *p)
+{
+	struct event_change ch;
+	ch.fd = fd;
+	ch.old_events = old;
+	ch.read_change = ch.write_change = 0;
+	if (events & EV_WRITE)
+		ch.write_change = EV_CHANGE_DEL;
+	if (events & EV_READ)
+		ch.read_change = EV_CHANGE_DEL;
+
+	return epoll_apply_one_change(base, base->evbase, &ch);
+}
+
+static int
+epoll_dispatch(struct event_base *base, struct timeval *tv)
+{
+	struct epollop *epollop = base->evbase;
+	struct epoll_event *events = epollop->events;
+	int i, res;
+	long timeout = -1;
+
+	if (tv != NULL) {
+		timeout = evutil_tv_to_msec(tv);
+		if (timeout < 0 || timeout > MAX_EPOLL_TIMEOUT_MSEC) {
+			/* Linux kernels can wait forever if the timeout is
+			 * too big; see comment on MAX_EPOLL_TIMEOUT_MSEC. */
+			timeout = MAX_EPOLL_TIMEOUT_MSEC;
+		}
+	}
+
+	epoll_apply_changes(base);
+	event_changelist_remove_all(&base->changelist, base);
+
+	EVBASE_RELEASE_LOCK(base, th_base_lock);
+
+	res = epoll_wait(epollop->epfd, events, epollop->nevents, timeout);
+
+	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
+
+	if (res == -1) {
+		if (errno != EINTR) {
+			event_warn("epoll_wait");
+			return (-1);
+		}
+
+		return (0);
+	}
+
+	event_debug(("%s: epoll_wait reports %d", __func__, res));
+	EVUTIL_ASSERT(res <= epollop->nevents);
+
+	for (i = 0; i < res; i++) {
+		int what = events[i].events;
+		short ev = 0;
+
+		if (what & (EPOLLHUP|EPOLLERR)) {
+			ev = EV_READ | EV_WRITE;
+		} else {
+			if (what & EPOLLIN)
+				ev |= EV_READ;
+			if (what & EPOLLOUT)
+				ev |= EV_WRITE;
+		}
+
+		if (!ev)
+			continue;
+
+		evmap_io_active(base, events[i].data.fd, ev | EV_ET);
+	}
+
+	if (res == epollop->nevents && epollop->nevents < MAX_NEVENT) {
+		/* We used all of the event space this time.  We should
+		   be ready for more events next time. */
+		int new_nevents = epollop->nevents * 2;
+		struct epoll_event *new_events;
+
+		new_events = mm_realloc(epollop->events,
+		    new_nevents * sizeof(struct epoll_event));
+		if (new_events) {
+			epollop->events = new_events;
+			epollop->nevents = new_nevents;
+		}
+	}
+
+	return (0);
+}
+
+
+static void
+epoll_dealloc(struct event_base *base)
+{
+	struct epollop *epollop = base->evbase;
+
+	evsig_dealloc(base);
+	if (epollop->events)
+		mm_free(epollop->events);
+	if (epollop->epfd >= 0)
+		close(epollop->epfd);
+
+	memset(epollop, 0, sizeof(struct epollop));
+	mm_free(epollop);
+}